CN107947097A - A kind of 10kV suspended insulated guide wires with the anti-lightning strike broken string of shielded layer - Google Patents

Abstract

The invention relates to a 10KV overhead insulated wire with a shielding layer to prevent lightning breakage. The insulated wire is set overhead by means of a pole tower equipped with a lightning arrester. The insulated wire includes a wire core and an insulating layer around it, and the outer surface of the insulated wire is wrapped and arranged. There are shielding layers connected to different arresters at both ends, the shielding layer is connected to the upper end of the arrester, the lower end of the arrester is connected to the grounding electrode of the tower, the grounding resistance of the tower is ≤30 ohms, and the shielding layer is a plain weave stainless steel wire mesh, The wire core is aluminum wire, and the insulating layer is made of cross-linked polyethylene; the insulated wire in the present invention has less metal consumables, is simple to manufacture, and has low cost. area.

Description

A 10kV overhead insulated wire with shielding layer for lightning protection

technical field

The invention belongs to the technical field of electric power, and in particular relates to a 10KV overhead insulated wire with a shielding layer to prevent lightning breakage.

Background technique

With the development of my country's economy and the increase in social demand for electricity, in order to cope with the sharp increase in electricity consumption, the country is constantly developing power plants and increasing power production. The power is produced by the power plant and then transmitted to the user through the wire. However, during the transmission process, it is often vulnerable to natural disasters and accidents. The most serious and frequent lightning strike accidents occur in areas where lightning activities are infrequent. It can meet the normal transmission requirements, but when passing through the lightning strike area with frequent activities, lightning strike accidents often occur, which may cause accidents such as accumulative flickering of insulators and lightning strike disconnection, and cause fire, damage to substation equipment, and power system Accidents such as interruptions affect the normal use of users. Due to the low lightning protection performance of insulated wires in our country, in order to protect the power system from lightning strikes, overhead insulated wires are used the most. Overhead insulated wires are currently the most used type of transmission wires, mainly based on the type and performance of overhead insulated wires. , a comprehensive analysis of the lightning protection measures for overhead insulated conductors. Definition of overhead insulated wire: a wire with a single or multiple layers of aluminum strands stranded on which an insulating layer is extruded. The so-called overhead line is relative to the cable, that is, the wire is erected by the tower at a certain height to transmit electric energy. For the high-voltage transmission and distribution network, the ground insulation of the overhead line is generally based on air. The previous distribution lines (except 10KV) 380V) generally use bare wires, but due to the complex power distribution environment in urban areas, short-circuit grounding and lightning strikes often occur, resulting in reduced power supply reliability. Therefore, insulated wires are generally used for overhead lines below 10KV Insulation layer), which is the so-called insulated overhead wire. Overhead wires are divided into low-voltage and high-voltage. There are many types of general models, such as JKLYJ*10KVA*50*100 overhead wires for street lamps, which shows the voltage, model, core cross-sectional area and length of the overhead wires. Compared with wire erected lines, the main advantages of this type of line are: ① It is conducive to improving and enhancing the safety and reliability of the power distribution system, greatly reducing the risk of personal electric shock casualties, insulated wires can prevent foreign objects from causing short circuits between phases, and reduce power outages during the operation of the combined pole line times, reduce the maintenance workload, and improve the utilization rate of line power supply; ②It is beneficial to urban construction and greening work, and reduces the amount of tree pruning along the line; ③It can simplify the structure of line pole towers, which can be laid along the wall, which not only saves line materials, but also beautifies ④ It is convenient for high voltage to penetrate into the load center to improve voltage quality and reduce power loss; ⑤ Save the space occupied by overhead lines and facilitate the passage of overhead lines in narrow passages. The line corridor is reduced, compared with the overhead bare wire, the line corridor can be reduced by 1/2; ⑥ saves the power loss of the line, reduces the voltage loss, and the line reactance is only 1/3 of the ordinary bare wire line reactance; Line service life and power distribution reliability; ⑧Reduce the gravity requirements of the line, reduce the investment in fittings, and reduce the labor intensity of workers when erecting wires; ⑨Reduce the insulation requirements for line support parts, and increase the number of circuits on the same pole; 10 Line technical status Improve, reduce the maintenance workload, extend the maintenance cycle, and reduce the power outage time due to maintenance. The disadvantages are: 1. The allowable current carrying capacity of the overhead insulated wire is smaller than that of the bare wire. After adding the plastic layer, the heat dissipation of the wire is poor. The general shape of the overhead insulated wire should be higher than usual. If the original 70mm2 wire is used, it must be equipped with 95mm2. 2. The wire diameter of the overhead insulated wire is larger, and with the addition of plastic sheath, the wire diameter is one grade larger than that of the steel-cored aluminum stranded wire with the same cross-section. 3. The discharge ability is not strong, and the lightning current cannot be discharged in time, resulting in frequent disconnection accidents. Insulated wires have many advantages, but the unit cost is higher than that of bare wires. Today we mainly analyze how to prevent lightning overvoltage from causing disconnection of overhead insulated wires.

Mechanism of insulated wire disconnection due to lightning strike: Lightning strikes, previously used bare wires will cause line flashover, especially when overhead insulated wires are struck by lightning, direct lightning or induced lightning acts on the wires, which will cause line flashover. At this time, the arc caused by the power frequency continuous flow is affected by the electromagnetic force, so that the arc flows rapidly to both sides of the lightning strike point of the wire, and the lightning current quickly flows into the earth through the arrester at the switch, transformer and other equipment, or the power frequency current burns Before the wire is broken, it will cause a trip, so a wire break accident rarely occurs. However, when the insulated wire is struck by lightning, the situation is completely different. The lightning overvoltage causes the insulator to flash over and break down the insulation layer of the wire. The insulation near the breakdown point prevents the arc from moving sideways along the surface of the wire. Thus, the arc can only burn at the point of breakdown. Power frequency arc currents up to thousands of amperes concentrate at the point of insulation breakdown and fuse the wires shortly before the circuit breaker trips.

Existing lightning protection measures for overhead insulated conductors: With the frequent occurrence of lightning strike accidents on my country's field power distribution transmission lines, people are paying more and more attention to the improvement of the lightning protection performance of overhead insulated conductors. According to the actual work summary, according to the actual line operation Experience and combined with local natural conditions, adapt measures to local conditions, take scientific and effective lightning protection measures to improve lightning protection performance, mainly include the following lightning protection measures for insulated wires: 1) Erection of overhead lightning protection lines. As a traditional effective lightning protection measure is the erection of overhead lightning protection lines, which mainly use the shielding effect of overhead lightning protection lines to protect power transmission lines. The efficiency of erecting overhead lightning protection lines is very high and the effect is obvious, but its initial investment cost is very high. Large, although personnel must be maintained in the later stage, the construction cost in the early stage is very high, and the winding effect is poor; 2) Install the outer gap arrester. Distribution lines are more extensive than lines that transmit power, so the protection measures for distribution lines are more difficult, and they are not necessarily 100% lightning-proof. We often use non-gap arresters in distribution lines, because non-gap arresters are not only It must bear the voltage in the process of transmitting electric energy, and also bear the lightning strike and lightning pressure in the accumulation process. Therefore, the gapless arrester is easy to be damaged, and the performance cannot be guaranteed. After extensive practical experience in recent years, the performance of the outer gap arrester It has attracted people's attention. The outer gap arrester is mainly combined with the zinc oxide arrester and the outer gap. In this way, the lightning protection performance in actual use is very good, and the safety of the distribution line is protected. However, the number of arresters used is large and the cost is high. ; 3) Increase the thickness of the insulating layer. The traditional overhead insulated wire itself has a certain insulation and lightning protection performance, but the performance is not high, and it cannot withstand high-intensity lightning strikes. It can be adjusted to local conditions according to the actual situation. According to different local conditions, the thickness of the insulation layer of the insulated wire can be increased. , Not all lines increase the thickness of the insulation layer, but increase the thickness of the insulation layer in areas that are prone to lightning strikes or frequent lightning activities to prevent lightning strikes; 4) Piercing arc-proof fittings. Its use mechanism is mainly installed on the load side near the line insulator, so that when struck by lightning, as long as the lightning voltage of the transmission line exceeds a predetermined value, the puncture motor of the arc-proof fittings and the grounding motor will be connected in series to form a flashover, thus forming If a short circuit occurs, the arc on the puncture-type arc-proof fittings will burn by itself, so as to protect the safety of the insulated wires of the distribution line and prevent damage from lightning strikes. In this way, it is necessary to destroy a certain power saving of the wires and damage the insulation layer, causing the wire to be easily oxidized. To sum up, all kinds of lightning protection measures have shortcomings of one kind or another. Some of them are not suitable due to the influence of geographical environment, resulting in insignificant lightning protection effect, or high cost, and some destroy the insulation layer of wires. Time-consuming and labor-intensive, it cannot be applied to actual work.

Contents of the invention

The present invention overcomes the shortcomings of the prior art and provides a 10KV overhead insulated wire with a shielding layer to prevent lightning breakage. The occurrence of lightning strike line accidents is avoided, and the reliability of power supply is improved.

Concrete technical scheme of the present invention is:

A 10KV overhead insulated wire with a shielding layer for lightning protection and disconnection. The insulated wire is set overhead by means of a tower. The insulated wire includes a wire core and an insulating layer around it. The key point is that the tower includes a terminal tower, a branch For pole towers and straight pole towers, lightning arresters are installed on the pole towers, and the outer surface of the insulated wire is wrapped with shielding layers that are connected to different lightning arresters at both ends, and the thickness of the insulation layer is not less than 3mm.

The shielding layer is provided with a disconnection at the terminal tower or branch tower involved in the insulated wire, and a lightning arrester is installed on the terminal tower or branch tower, and the disconnection of the shielding layer is connected to the lightning arrester on the corresponding tower.

The shielding layer is connected to the upper end of the lightning arrester, and the lower end of the lightning arrester is connected to the grounding electrode of the tower, and the grounding resistance of the tower is ≤30 ohms.

The shielding layer is plain weave stainless steel wire mesh.

The wire core is aluminum wire.

The material of the insulating layer is cross-linked polyethylene.

The beneficial effects of the present invention are: the insulated wires in the present invention have the same shape, the same specifications and the same technical parameters as the existing insulated wires in the field, and the insulated wires can be equipped with lightning protection against broken wires after one-time construction during the wiring construction Function, no need for additional construction, can effectively shorten the construction time, improve installation efficiency, and is easy to use and manufacture; the shielding layer can also prevent trees and other external forces from damaging the insulation layer of overhead insulated wires under normal conditions. , can be used as a channel for releasing lightning current, through the connection with the lightning arrester, the lightning current of the insulated wire can quickly leak into the earth through the lightning arrester after being struck by lightning. It protects the 10KV overhead insulated wires from the threat of lightning strikes; the shielding layer is made of plain weave mesh, which can greatly reduce the loss of stainless steel wires, reduce costs, and improve the lightning protection effect. It is suitable for special places such as open areas where lightning is frequent, and the shielding layer It can be disconnected at the position of the tower, and then connected to the lightning arrester, without special reconnection, so as to achieve the effect of lightning protection for each section of the line. At the same time, under normal circumstances, there is The insulating layers of the overhead insulated wires are separated, and the arrester can work in the case of lightning overvoltage, but not put into operation under normal conditions, which greatly reduces the maintenance cost of the arrester. The insulated wire in the invention has a wide application range and a simple structure, and does not require each tower to be equipped with a lightning arrester, thus greatly reducing the number of lightning arresters used.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

FIG. 2 is a schematic diagram of an enlarged structure of A in FIG. 1 .

In the accompanying drawings, 1. Lightning arrester, 2. Tower, 3. Wire core, 4. Insulation layer, 5. Shielding layer.

Detailed ways

The present invention relates to a 10KV overhead insulated wire with a shielding layer to prevent lightning breakage. The insulated wire is set overhead by means of a tower 2. The insulated wire includes a core 3 and an insulating layer 4 around it. The tower 2 includes a terminal For towers, branch towers and straight towers, the tower 2 is equipped with a lightning arrester 1, and the outer surface of the insulated wire is wrapped with a shielding layer 5 with two ends connected to different lightning arresters 1, and the thickness of the insulating layer 4 is not less than 3mm.

Concrete embodiment, as shown in Fig. 1 and Fig. 2, pole tower comprises terminal pole tower, branch pole tower and linear pole tower, in order to reduce the setting quantity of lightning arrester 1, shielding layer 5 is set at the terminal pole tower or branch pole tower place at both ends of the line involved in the insulated wire At the disconnection, the lightning arrester 1 is only installed on the terminal tower or the branch tower, and the disconnection of the shielding layer 5 is connected to the lightning arrester 1 on the corresponding tower 2, thus greatly reducing the number of lightning arresters 1 and greatly reducing the installation cost.

In order to prevent the insulating layer 4 between the core 3 and the shielding layer 5 from being broken down, the thickness of the insulating layer 4 is set to 4 mm. If it is less than this thickness, the insulating layer 4 is easily broken down. If it is greater than this thickness, the insulating layer 4 Manufacturing costs will increase significantly.

The shielding layer 5 is connected to the upper end of the arrester 1, and the lower end of the arrester 1 is connected to the ground electrode of the tower 2 so as to be connected to the earth, which can better attract lightning current and then leak into the earth through the arrester 1. The tower 2 with the arrester 1 installed When the lightning strikes the overhead insulated wire, the lightning first hits the shielding layer 5 on the periphery of the wire, and the lightning current moves to both sides along the shielding layer 5, and moves to the terminal tower or branch with the arrester 1 When the tower is erected, the lightning current is introduced into the earth through the arrester 1, so that the lightning will neither break the insulated wire nor cause the line trip due to lightning overvoltage. At the same time, under normal circumstances, the shielding layer 5 also serves to prevent the 4 When damaged by external force, in addition, if the insulating layer 4 is damaged by lightning breakdown, the shielding layer 5 and the core 3 are charged at the same potential, and the arrester 1 will prevent the core 3 from conducting with the ground and prevent grounding accidents. The insulated wire in the present invention is suitable for areas with more lightning, and the shielding layer 5 is a plain weave stainless steel wire mesh, which greatly reduces the metal consumables used;

The wire core 3 is an aluminum wire, which is used to transfer electric energy, and the transmission efficiency is high. The insulating layer 4 is made of cross-linked polyethylene, and the insulating layer 4 between the wire core 3 and the shielding layer 5 can prevent the arrester 1 from being at the working voltage for a long time. Reduced maintenance of arrester 1;

The specific installation method when in use is as follows: erect the insulated wire with shielding layer 5 on the pole tower 2, put the insulated wire into the insulator after tightening the wire, bind it tightly, and install a set of wires on the terminal towers or branch towers on both sides respectively Lightning arrester 1, the structure of the straight pole tower in the middle does not make any changes, and the grounding downconductor and grounding electrode are installed on the pole tower 2 installed with lightning arrester 1. The grounding resistance is ≤30 ohms to ensure the normal conduction of lightning current. Under normal circumstances, it can also avoid Damage to the insulating layer 4 by external force can be used as a channel for releasing lightning current in the event of a fault. Through the connection with the arrester 1, the lightning voltage can be released when the protected insulated wire is struck by lightning, and the core 3 and insulating layer 4 of the insulated wire are protected. The shielding layer 5 is made into a plain weave mesh, which can greatly reduce the loss of stainless steel wire, reduce costs, and improve the lightning protection effect. It is suitable for special places such as open areas with frequent lightning, and the shielding layer 5 is disconnected at the terminal tower or branch tower, It is connected to the corresponding lightning arrester 1 without special reconnection to achieve the effect of lightning protection for each section of the line. At the same time, under normal circumstances, there is an insulating layer 4 between the core 3 and the shielding layer 5. The lightning arrester 1 can It works under the condition of overvoltage, but does not put into operation under normal conditions, which greatly reduces the maintenance frequency and maintenance cost of the lightning arrester 1 . The structure of the insulated wire in the present invention is simple, easy to manufacture and put into use, one-time erection construction can effectively shorten the construction time, improve installation efficiency, and greatly save the number of lightning arresters 1 to be installed.

The insulated wires in the present invention have the same shape, the same specifications and the same technical parameters as the existing insulated wires in the field. The insulated wires can have the function of lightning protection and disconnection after one-time construction during the wiring construction, and no additional construction is required. It can effectively shorten the construction time, improve the installation efficiency, and is convenient to use and manufacture; the shielding layer 5 can also avoid damage to the insulating layer 4 in the overhead insulated wire by trees and other external forces under normal conditions, and can be used as a lightning release device under fault conditions. The current channel, through the connection with the lightning arrester 1, the lightning current of the insulated wire can quickly leak into the earth through the lightning arrester 1 after being struck by lightning, so as to protect the 10KV overhead insulated wire from the threat of lightning strike; the shielding layer 5 is made into a plain weave mesh, which can greatly Reduce the loss of stainless steel wire, reduce the cost, and improve the lightning protection effect. It is suitable for special places such as open areas with frequent lightning, and the shielding layer 5 can be disconnected at the position of the pole tower 2, and then connected to the arrester 1 without special reconnection. To achieve the effect of lightning protection for each section of the line, and under normal circumstances, the wire core 3 of the overhead insulated wire and the shielding layer 5 of the overhead insulated wire are separated by the insulating layer 4 of the overhead insulated wire, and the arrester 1 can be used when lightning passes. work under the condition of high voltage, but not put into operation under normal conditions, which greatly reduces the maintenance cost of the arrester 1 . The insulated wire in the present invention has a wide application range and a simple structure, and does not require each tower 2 to be equipped with a lightning arrester 1, thus greatly reducing the number of lightning arresters 1 used.

Claims (6)

1. A 10KV overhead insulated wire with a shielding layer for lightning protection and disconnection, the insulated wire is set overhead by means of a tower (2), the insulated wire includes a core (3) and an insulating layer (4) on its periphery, its characteristics In that: the tower (2) includes a terminal tower, a branch tower and a straight tower, the tower (2) is equipped with a lightning arrester (1), and the outer surface of the insulated wire is wrapped with two ends that are respectively different from the lightning arrester (1). ) connected to the shielding layer (5), the thickness of the insulating layer (4) is not less than 3mm. 2. A kind of 10KV overhead insulated conductor with shielding layer lightning protection according to claim 1, characterized in that: the shielding layer (5) is provided with a disconnection at the terminal tower or branch tower, A lightning arrester (1) is installed on the terminal pole tower or branch pole tower, and the disconnection of the shielding layer (5) is connected with the lightning arrester (1) on the corresponding pole tower (2). 3. A kind of 10KV overhead insulated wire with a shielding layer for lightning protection according to claim 1, characterized in that: the shielding layer (5) is connected to the upper end of the arrester (1), and the arrester ( The lower end of 1) is connected to the grounding electrode of the pole tower (2), and the grounding resistance of the pole tower (2) is ≤30 ohms. 4. A 10KV overhead insulated conductor with a shielding layer for protection against lightning breakage according to claim 1, characterized in that: said shielding layer (5) is plain weave stainless steel wire mesh. 5. A 10KV overhead insulated wire with a shielding layer for protection against lightning breakage according to claim 1, characterized in that: the wire core (3) is an aluminum wire. 6. A 10KV overhead insulated wire with a shielding layer for protection against lightning breakage according to claim 1, characterized in that: the insulating layer (4) is made of cross-linked polyethylene.